Device for imparting motion to an optical lens

ABSTRACT

A device for imparting motion to an optical lens while the latter is held in contact with the working surface of a lensgrinding, smoothing or polishing tool, comprising a lens-holder mounted on a shaft which, at spaced-apart points along its length, passes through or is connected to at least two driven eccentric bearing assemblies of which one is of adjustable eccentricity and the other has two eccentrics driven at two speeds which are in selected ratios to each other so that the shaft is given a substantially uniform but substantially nonrepeating motion by the said eccentric bearing assemblies.

United States Patent 51 May 30, 1972 Wylde [54} DEVICE FOR IMPARTING MOTION TO AN OPTICAL LENS [72] Inventor: Stephen Jack Wylde, Croydon, England [73] Assignee: J. L. S. Limited, Croydon, England [22] Filed: Jan. 12, 1971 [21] Appl. No.: 105,813

[52] U.S.CI. ..5l/l60,5l/l20 [51] Int. Cl ..B24b 13/02 [58] FieldofSeareh ..5l/l57, 160, 119, 120

[56] References Cited UNITED STATES PATENTS 3,172,241 3/1965 Habenicht ..5 H120 3,383,806 5/1968 Stratemeyer ..5 III 19 X 3,552,899 1/1971 Tagnon ..51/160 Primary Examiner-Othell M. Simpson Attamey-Berman, Davidson and Herman [57] ABSTRACT A device for imparting motion to an optical lens while the latter is held in contact with the working surface of a lensgrinding, smoothing or polishing tool, comprising a lensholder mounted on a shaft which, at spaced-apart points along its length, passes through or is connected to at least two driven eccentric bearing assemblies of which one is of adjustable eccentricity and the other has two eccentrics driven at two speeds which are in selected ratios to each other so that the shaft is given a substantially uniform but substantially non-repeating motion by the said eccentric bearing assemblies.

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Patented May 30, 1972 4 Sheets-Sheet 2 lnvenlor STEPHEN cf WVLflE, MIQWM Patented May 30, 1972 4 Sheets-Sheet 5 lnvenlor STEPHEN c/. WYLflE,

Patented May 30, 1972 4 Sheets-Sheet 4 lrwenlor STEPHEN WYLDE,

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DEVICE FOR IMPARTING MOTION TO AN OPTICAL LENS This invention relates to machines for grinding, smoothing or polishing optical lenses. More specifically, it relates to a device for imparting motion to an optical lens while the latter is held in contact with the working surface of a lens-grinding, smoothing or polishing tool.

Various proposals have been made in the past for producing relative motion between an optical lens and the working surface of a lens-grinding, smoothing or polishing tool. In some arrangements, one or other of the two parts is held stationary, while the other one is moved in a reciprocating, circular or gyratory motion. In some other machines, both parts are moved so as to produce a compound motion between them. A disadvantage however of all these prior proposals is that they do not provide a sufficiently uniform, substantially non-repeating motion.

It is therefore an object of the present invention to provide an arrangement which gives rise to more uniform motion of a non-repeating nature than that given by the machines used hitherto.

To this end, the present invention is directed towards a device for imparting motion to an optical lens while the latter is held in contact with the working surface of a lens-grinding, smoothing or polishing tool, which device comprises a lensholder mounted on a shaft which, at spaced-apart points along its length, passes through or is connected to at least two driven eccentric bearing assemblies of which one is of adjustable eccentricity and the other has two eccentrics. driven at two speeds which are in selected ratios to each other so that the said bearing assemblies impart to the shaft a substantially uniform but substantially non-repeating motion as herein defined.

The term non-repeating motion as used herein is not to be interpreted too literally. For example, a motion which does not repeat itself more than once in 2,000 cycles is considered to be non-repeating as far as the present invention is concerned. Accordingly, the said term is to be understood as including any motion which does not repeat itself more than once in 500 cycles.

A lens-moving device of this construction can be used in various forms of machine, but it is especially applicable to a machine comprising a hollow main body containing a stationary holder for a lens-grinding, smoothing or polishing too] together with a motor for driving a pump which serves to deliver an abrasive slurry to the working surface of the tool, and a hollow work head containing another motor which drives a projecting lens-moving device adapted to move a lens in a desired motion while it is in contact with the working surface of the tool. The work head is pivotally mounted on the hollow main body so that it can be easily moved out of its working position in order to gain access to the tool and to the lens-moving device, the latter being arranged to extend into the hollow main body through an opening in the latter when the head is in its working position.

An example of a lens-moving device and a machine incorporating it in accordance with the invention is illustrated in the accompanying drawings, in which:

FIG. 1 is a side view of the machine;

FIG. 2 is a plan view of the machine shown in FIG. 1 with the work head removed;

FIG. 3 is a front view of the machine;

FIG. 4 is a vertical section of an enlarged scale through the work head of the machine; and

FIGS. 5-7 are sections taken on the lines V-V, VI-VI and VIIVII respectively in FIG. 4.

The machine shown in the drawings comprises a hollow main body containing a stationary vice or other holder 12 for a lens-grinding, smoothing or polishing tool 14. In this particular instance, the smoothing tool 14 has an upper concave surface 16 for polishing a convex surface on a lens 18, but it could equally well be of mushroom shape so as to have an upper convex surface for polishing a concave surface on the lens. Usually the tool 14 will be provided with a wear-taking pad (not shown) on its upper surface 16, the pad being attached to the surface 16 by an adhesive and comprising a layer of woven metal fabric, expanded metal foil or some such material.

The vice is opened and closed so as to release and lock the tool 14 in position by an air cylinder 20. This has an air-supply pipe 22 which is controlled by a hand-operated air valve 25 on the front portion of the main body 10. A second pipe 26 leads from the valve 24 to an inlet orifice 28 in the lower surface of the main body 10 for connection to a suitable source of compressed air (not shown). The vice l2 and the air cylinder 20 are both arranged within the hollow main body 10 so as to be well enclosed. The main body 10 also contains a pump motor 30 which serves to drive a pump 32 provided with an inlet located in a sump or reservoir 34 removably supported below the hollow main body 10. The pump has a delivery pipe 36 leading to a point 36a at the upper end of a hollow shaft 37 the lower end of which lies just above the tool 14 so that, in operation of the pump, the pipe 36 supplies an abrasive slurry through the hollow shaft 37 from the sump 34 to the working surface 16 of the tool 14. The slurry thus washes over the working surface of the tool continuously during operation of the machine and is returned to the sump through the pipe 38.

Mounted above the main hollow body 10 is a hollow work head 40 which contains an electric motor 44 (FIG. 4) arranged to drive a lens-moving device 42 (FIG. 1). The device 42 projects downwards from the forward lower surface of the work head 40 and is designed to move the lens 18 in a desired motion while the latter is held in contact with the working surface 16 of the tool 14. In order that the head may be easily moved out of its working position (the position shown in FIG. 1) so as to give access to the tool and to the lens-moving device, the head 40 is pivotally mounted at 48 on lugs 50 formed on the upper part of the hollow main body 10. In this way the head can be swung upwards in a clockwise direction as the machine is shown in FIG. 1 about the horizontal axis provided by the pivotal mounting 48. It will also be noted that the lens-moving device 42 is arranged to extend into the hollow main body 10 through an opening 52 in the latter when the head is in its working position. This has the advantage that slurry is not thrown out of the machine during the grinding, smoothing or polishing operations, and it also helps to keep the working parts of the machine in better condition.

As already indicated, one of the disadvantages of existing machines is that the means for producing relative movement between the lens and the tool doe not provide a sufficiently uniform, substantially non-repeating motion. To overcome this drawback, the machine of the present invention has a new form of lens-moving device 42 which is illustrated in detail in FIGS. 4-7 of the drawings.

As shown in FIG. 4, the lens-moving device includes the hollow shaft 37, which has already been referred to, as one of the means by which slurry is fed to the working surface of the tool. This shaft is in fact held against rotation about its axis by radial stubs 50 (see also FIG. 6) which project from the middle portion of the shaft and which are arranged for sliding movement in sleeves 52, the sleeves 52 being in turn located in a ring 54 having radial arms 56 which slide in fixed sleeves 58 and which project at right angles to the stubs 50. In this way the shaft 27 is held against rotation while being free to gyrate or to follow some other motion not involving rotation about its axis.

Above and below the radial arms 50, the shaft 37 passes through or is connected to eccentric bearing assemblies 60 and 62. The upper assembly 60 comprises a driven eccentric 64 (see also FIG. 5) which can be angularly adjusted by hand to an extent determined by the length of two slots 66 which each have a locking pin or screw 48 on the eccentric 64 projecting into them. As shown in FIG. 4, a self-aligning ball bearing 70 is carried by the eccentric 64, the upper end of the hollow shaft 37 passing through the bearing 70. The eccentric bearing assembly 60 also includes a bush 72 to which is attached a pulley 74 arranged to be driven by a belt 76 from a drive pulley 78. The driven pulley 74 is mounted on a ball bearing 80 having a mounting 82 which is securely fixed to the casing of the work head by pillars 84. It will also be seen from FIG. 4 that the assembly 50 58 illustrated in FIG. 6 for preventing rotation of the shaft 37 is secured to the underside of the bearing mounting 82.

The lower eccentric bearing assembly 62 differs from the bearing 60 in that it has two driven eccentrics 86 and 94 one arranged within the other. A ball bearing 88 transmits the motions of these two eccentrics to the shaft 37 which passes through the bearing 88. As shown in FIGS. 4 and 7, the inner eccentric 86 has a radial arm 90 which extends over and beyond the outer eccentric 94 and is driven by a stud 92 on a drive pulley 96, the pulley 96 being driven through a belt 98 from a drive pulley 100. The outer eccentric 94 is driven by a further pulley 102 attached to the underside of the eccentric 94 and of larger diameter than the pulley 96, the pulley 102 being rotatably mounted on a ball bearing 104 and being driven by a further drive pulley 106 through a belt 108. In this way it is ensured that the eccentricity of the bearing assembly 62 is changed constantly during rotation of the two eccentrics 86 and 94.

The drive pulleys 78, 100 and 106 are mounted on a common shaft 110 (or on two co-axial shafts), the shaft 110 being driven by the electric motor 44.

By means of the lens-moving device 42 described above, the shaft 37 can be made to gyrate or follow other compound rotary movements without rotating about its own longitudinal axis. The actual motion can be varied over a very wide range by virtue of the fact that the eccentricity of the bearing assembly 60 can be adjusted by hand as desired while the eccentricity of the other bearing assembly 62 is varied automatically during operation. As a result, the shaft 37 has an adjustable, substantially uniform, non-repeating motion which is not given by existing machines. Needless to say, this motion can be varied further by changing the sizes of the pulleys which are provided on the shaft 110 to impart rotary motion to the eccentrics of the eccentric bearing assemblies.

I claim:

1. A device for imparting motion to an optical lens while the latter is held in contact with the working surface of a tool, the said device comprising a lens-holder adapted to hold a lens in contact with a tool, a shaft on which the lens-holder is mounted, a first driven eccentric bearing assembly in driving connection with the shaft at one point along the length thereof, a second driven bearing assembly in driving connection with the shaft at a second point along the length thereof,

said first driven bearing assembly having an eccentric of adjustable eccentricity, and said second driven bearing assembly having two eccentrics arranged to be driven at different speeds in selected ratios to each other whereby the said bearing assemblies impart to the shaft a substantially uniform but substantially non-repeating motion" as herein defined.

2. A device according to claim 1, in which means are provided for holding the shaft against rotation about the longitudinal axis thereof while leaving the shaft free to gyrate.

3. A device according to claim 2, in which the means for holding the shaft against rotation about the longitudinal axis thereof comprise radial stubs which project from the shaft and are arranged for sliding movement in a ring which is similarly provided with radial arms arranged for sliding movement and projecting at right angles to the radial stubs.

4. A device according to which the claim 1, in which the eccentric of the first bearing assembly is arranged to be angularly adjusted to vary the eccentricity of the bearing assembly and to be releasably locked in a selected position of adjustment.

5. A device according to claim 4, in which the first bearing assembly comprises a single driven pulley by means of which the eccentric is rotated.

6. A device according to claim 4, in which the first bearing assembly comprises a sin le driven pulley by means of which the eccentric is rotated, t e said driven pulley being rotatably supported on a fixed mounting to which means for holding the shaft against rotation about the longitudinal axis thereof are also secured.

7. A device according to claim 1, in which the two eccentrics of the second bearing assembly are arranged one within the other.

8. A device according to claim 1, in which the second bearing assembly includes two independently driven pulleys, one for rotating one eccentric of the said bearing assembly and the other for rotating the other eccentric of the said bearing assembly.

9. A device according to claim 7, in which the inner eccentric of the second bearing assembly has a radial arm which extends over and beyond the outer eccentric and is driven by a stud on a driven pulley associated with the said inner eccentric.

10. A device according to claim 1, in which the two eccentric bearing assemblies are driven by three drive pulleys mounted on a common shaft.

11. A device according to claim 1, in which the shaft passes through two self-aligning ball bearings carried by the two eccentric bearing assemblies. 

1. A device for imparting motion to an optical lens while the latter is held in contact with the working surface of a tool, the said device comprising a lens-holder adapted to hold a lens in contact with a tool, a shaft on which the lens-holder is mounted, a first driven eccentric bearing assembly in driving connection with the shaft at one point alOng the length thereof, a second driven bearing assembly in driving connection with the shaft at a second point along the length thereof, said first driven bearing assembly having an eccentric of adjustable eccentricity, and said second driven bearing assembly having two eccentrics arranged to be driven at different speeds in selected ratios to each other whereby the said bearing assemblies impart to the shaft a substantially uniform but substantially ''''non-repeating motion'''' as herein defined.
 2. A device according to claim 1, in which means are provided for holding the shaft against rotation about the longitudinal axis thereof while leaving the shaft free to gyrate.
 3. A device according to claim 2, in which the means for holding the shaft against rotation about the longitudinal axis thereof comprise radial stubs which project from the shaft and are arranged for sliding movement in a ring which is similarly provided with radial arms arranged for sliding movement and projecting at right angles to the radial stubs.
 4. A device according to which the claim 1, in which the eccentric of the first bearing assembly is arranged to be angularly adjusted to vary the eccentricity of the bearing assembly and to be releasably locked in a selected position of adjustment.
 5. A device according to claim 4, in which the first bearing assembly comprises a single driven pulley by means of which the eccentric is rotated.
 6. A device according to claim 4, in which the first bearing assembly comprises a single driven pulley by means of which the eccentric is rotated, the said driven pulley being rotatably supported on a fixed mounting to which means for holding the shaft against rotation about the longitudinal axis thereof are also secured.
 7. A device according to claim 1, in which the two eccentrics of the second bearing assembly are arranged one within the other.
 8. A device according to claim 1, in which the second bearing assembly includes two independently driven pulleys, one for rotating one eccentric of the said bearing assembly and the other for rotating the other eccentric of the said bearing assembly.
 9. A device according to claim 7, in which the inner eccentric of the second bearing assembly has a radial arm which extends over and beyond the outer eccentric and is driven by a stud on a driven pulley associated with the said inner eccentric.
 10. A device according to claim 1, in which the two eccentric bearing assemblies are driven by three drive pulleys mounted on a common shaft.
 11. A device according to claim 1, in which the shaft passes through two self-aligning ball bearings carried by the two eccentric bearing assemblies. 